As the earth's population continues to grow and the global market for products expands, safe transportation for goods becomes increasingly important. Goods are often transported by a carrier having some form of platform upon which the goods are placed, such as, but not limited to, a flat bed trailer. Any movement of the goods could result in damage to the goods and/or create a safety hazard, for example if items began falling off the trailer thereby causing a motor vehicle accident. A further safety hazard can arise as a result of cargo shifting sufficiently to create an unbalanced load thereby adversely affecting the vehicle performance. This can prove especially dangerous when the flat bed trailer is cornering as the cargo shift may have increased the propensity for the trailer to rollover. The goods must therefore be secured in order to prevent any moving or shifting. Various tie down assemblies have been developed for this purpose.
The tie down straps are typically fastened and tensioned with the aid of winch having a manual ratchet mechanism. Such ratchet mechanisms are known in the art, for example, as shown in U.S. Pat. Nos. 4,045,002 and 5,853,164, and may be used for several fastening applications. The inherent limitation with these systems is the lack of monitoring and appropriate automatic adjustment of the strap tension during transit. This problem is a very common concern for flatbed trailers carrying cargo for the transportation industry. Operators are left wondering if they have adequately secured their cargo before departure and especially during transit, when the contents may shift slightly, adversely impacting on the tension of the strap and on the load distribution. Another weakness with the manual ratchet mechanism is the risk of injury to the operator. To manually secure tie downs, operators have to exert large forces, which often lead to physical injury.
An automatic take-up winch is taught in U.S. Pat. No. 4,036,476 to Douce. The Douce device employs an actuating unit that advances the winch by applying force on the teeth of the ratchet wheel, one tooth at a time. While the automatic take-up winch of the '476 patent overcomes the deficiency of the strictly manual winches, it suffers from a number of its own deficiencies. For example, because the Douce winch relies on the direct application of force against a tooth of the ratchet wheel, the force required is very high. The device therefore requires a strong source of pressure, which can be problematic given the small amount of available space below the carrier. In addition, the Douce invention is susceptible to failure as a result of debris build-up on the ratchet wheel teeth since the actuating unit needs to directly engage each tooth. The constant force being applied to the teeth also leads to increased wear of the teeth such that over time they will require replacement. Furthermore, the entire actuating unit and winch is one pre-formed unit such that the actuating unit may not be used in association with the winches that are already mounted on a carrier.
There are also no systems in place to monitor the tension of the retaining straps holding the cargo of a carrier in place and provide feedback to the operator of the carrier. The current tie down winches used on cargo carriers employ a passive mechanical system that does not monitor the condition or effectiveness of the system.
Accordingly, it is an object of an embodiment of the present invention to provide an automated tie down mechanism having a monitoring and active response system.
It is a further object of an embodiment of the present invention to provide an automated tie down mechanism that can be used with the existing winches on a carrier.
It is a further object of an embodiment of the present invention to overcome the deficiencies noted above.
Other objects of the invention will be apparent from the description that follows.